I am talking of prepaid, mobile handsets, and not fixed line phones

Hi,
I have heard that Tata Indicom offers a scheme where in two Tata indicom subscribers (Prepaid with mobile Handset) can talk free of cost, even if they are located in different circles (ideally an STD scenario). I would like to know if there actually exists any such offer, and if yes, i would be interested in getting the details.
PS: I am talking of prepaid, mobile handsets, and not fixed line phones.
Thanking you in advance.